Also known as the gas plant, Fraxinella, the false Dittany, and its Latin name, Dictamnus albus, this perennial grows from Southern Europe, through the Mediterranean area, through the Middle East, and into Northern China. It grows to be about a meter tall, and flowers in late spring with white, pink, or purple blossoms. Specialized glands in the plant's leaves and flowers release a citrus-scented oil that accumulates into waxy buildup that helps the plant conserve water. This wax also contains psoralens, which can cause nasty chemical burns when skin comes in contact with the wax and sunlight simultaneously.

Now for the interesting part: On cooler days, the volatile oil congeals into wax as stated above. However, when the temperature is warmer, it melts off the plant and inundates the air surrounding it. As it turns out, when the wind is still enough for a high concentration of this vapor to build up, it becomes highly flammable, to the extent that it will ignite with only a tiny spark, or even spontaneously now and again. Fortunately for the bush, hot blue flames consume all of the volatile oil in a matter of a few seconds, leaving its leaves and flowers basically unharmed.

Of course, the growth of such a plant in the Middle East begs the question of whether Moses witnessed a miracle, or simply a Dictamnus albus going off in the night. Indeed, in the NIV translation of Exodus 3-2 as quoted above we have Moses witnessing the bush on fire (but not consumed by it) from a distance, with no mention of the flames once he was closer to it -- this omission holds in the King James version as well. While the theory is pure conjecture, it's mentioned here and there in printed media and on the internet, and probably bears repetition here if only because it is such an interesting possibility.